Telemetric data transmission techniques are known from the telemetric measuring device described in the U.S. Pat. No. 4,625,733 to Saynajakangas, the subject matter of which is incorporated herein by reference. Such equipment is used for detecting and telemetric transmission of heartbeat and EKG signals to a separate wrist-worn receiver, measurement and display device, to be used for personal heartbeat rate monitoring during exercise and sports activities. The telemetric transmitter mainly consists of transmitter electronics encapsuled in a casing and fastened to a belt holding the transmitter in place and of electrodes electrically connected to the transmitter electronics and located on the surface of the belt towards the user's skin on both sides of the transmitter electronics.
In the copending U.S. patent application Ser. No. 07/885,607, belonging to the assignee of the present application, is shown an improved telemetric transmitter unit, where the telemetric transmitter unit is coupled to the electrodes by means of a conductive plastic layer. In fact, the electrodes themselves may be formed as a part of the conductive plastic layer. The transmitter electronics and the conductive plastic layers are molded or jointed together with plastic material to form an integrated, waterproof transmitter unit.
The prior art telemetric transmitter units, which are used for heartbeat rate monitoring during exercise and sport performance, are more or less invariably attached to the chest of the user by means of elastic straps connected to the transmitter unit and tied more or less tightly around the upper body of the user. The electrodes and thus the whole assembly of the transmitter unit and the straps are attached in direct contact with the skin of the user, in order to ensure proper contact of the electrodes with the skin of the user and thus proper operation and measuring from the beginning of the performance or measuring cycle.
This direct contact of the electrodes with the user's skin is not desirable. The material of the electrodes must be subject of careful design considerations in order to avoid any allergic reactions to the electrode material. Skin chafing due to the sliding of the electrode belt and the electrodes on the body during extensive motion over long periods is another problem. In sports clubs and events, where many individuals may be tested using the same equipment, dermatological disease transfer may occur from one user to another. A very frequent washing of the electrode belts, on the other hand, reduces the life of the elastic straps of the electrode belt.